This is inspired from TestExoPlayerBuilder.
Adding this class has a few advantages:
- It makes testing easier for apps by configuring Transformer for unit
tests (for example, by setting the clock).
- It removes the Transformer setters that apps should not use for unit
testing (for example, the video MIME type should not be set because
it would cause Transformer to transcode.
- It allows us to add additional setters in the future, for example to
build a Transformer that always fails.
PiperOrigin-RevId: 704181927
1a7da45dd9